Discharge-device system



June 16, 1925. 1,542,381 l Y J. c. GABRIEL ET A1. K

DISCHARGE DEVICE SYSTEM Fundggm 15, A1924 f -EMM.

1/0/7/7 Edy/6% n /W/d mE/fm,

Patented Julie 16, 1925.

UNITED STATES JOHN C. GABRIEL, OF NEWVYORK, N. Y.,

AND Aiavrn e. LANDEEN, or CALDWELL,

NEW JERSEY, ASSIGNORS TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION 0F NEW YORK.

DISCHARGE-DEYICE SYSTEM.

To all whom t may concern:

Be itl known that we, JOHN C. GABRIEL and Amun G. LANDEEN, citizens of the. United States of America, residing at New York city, in the county and State of New York, and Caldwell, in the county of Essex and State of New Jersey, respectively, have invented certain new and useful Improvements in Discharge-Device Systems, of which the following is a full, clear, concise, and exact description. f

This invention relates broadlyto high frequency signal transmitting circuits, and more particularly to an electrontube radio transmitter having means for establishing and maintaining a constant negative potential on the grids of the various electron tubes constitutingparts of a. complete high frequency transmitting circuit.

One of the objects of the invention is to provide a circuit arrangement in an electron tube transmitting system whereby a unitary means is provided for deriving a negative grid potential for a plurality of the electron tubes in the transmitting system.

Still another object of the invention is to provide an electron tube transmitting circuit arrangement wherein the power amplifier ytubes of the system are provided with a potentiometer circuit in shunt with the input circuit of the power amplifier, insuring a relatively large continuous flow of current therethrough,-with taps taken from a plurality of points on the potentiometer to connections with the grid circuits of a plurality of tubes in the` transmitting system for controlling the negative grid potentials of said-tubes from a single' location in the system.

Still another object of the invention is to provide means in the input circuit of the power amplifier of a radio transmitting apparatus for controlling the negative potential vof the grids of the modulator and the speech amplifier in the electron tube transmitting system. y

A still further object of the inventionis yto provide automatic lcompensation means in the power amplifier circuit of a radio transmitter for the effectsv of momentaryy Appucaaon inea June 13, 1924. seriai No. 719,698.

so locate a resistance in a wave relaying system that connections may be taken from the said unit to the grid circuits of the tubes in different parts of the system for deriving negative grid potential for the various tubes from a common source.

Other objects of the invention will be understood from the specification hereinafter. following by referenceto'the accompanying diagram which illustrates the connections invan' electron tube radiotransniitting system equipped with our invention.

Radio transmitting apparatus employing a large number of electron tubes is complicated by the number of independent grid cont-rol circuits, the value of negative poten-r tial on the grids of the tubes in one part of the system-being entirely inde endent of the potential existing on the gri sof the tubes .1n another part of the system.r ln the case of the impression of energy 'of' unusually large amplitude upon the speech circuit of a radio transmitter,`impulses of unusually large amplitude maybe caused to flow in the plate circuit of the power amplifier with detrimental results. By the arrangement described in the present invention a unitary resistance element or potentiometer is provided in the input circuit of the power amplifier providing a leak ath for the grid circuit of the power amp ifier and a source of negative potential for the grid circuits of the modulator and the speech amplifier. The value of' negative potential on the grids of both the modulator and the speech amplifier tubes becomes dependent upon the passage of current in the potentiometer circuit of the power amplifier. The location of the resistance device in the power amplifier circuit and the variable tap 'connections leading from points on this resistance permits automatic compensation for the effects of momentary high potentials impressed u 'on the modulator from the speech circuit. n this arrangement the existence of lmomentary high potentials impressed upon the modulator from the speech circuitwhile tending to cause impulses of unusually large amplitude in the plate circuit of the power amplifier, will also cause a series of momentarily large impulses of current to flow tothe grids of the power amplifiers. This increased current fiow in the leak path results in momentarily increased negative potential upon the grids which will tend to increase the 1mpedance of all the tubes in the system having their grids polarized from this reslstance, which action operates to compensate for the operation of the system normally and to prevent distortion at the increased amplitude of impulses in the speech amplifier circuit. The leak resistance is located in a position where it is influenced by effects originating from the speech amplifier circuit, enabling the conditions 1n such c1rcuit to be promptly repeated and caused to affect the characteristics of the negatlve p otential device in the ower amplifier circuit, automatically7 adjusting the wor-king characteristics for all the tubes in the system.

Referring more particularly to the drawing, reference character 1 represents` the modulator circuit for the radio transmitter under control of microphone circuit indicated by reference character 2. The nuorophone circuit includes the primary windlng 3 of a transformer 4 inductively related to the secondary winding 5 connected in the grid circuit of the modulator 1. The output circuit of the modulator 1 includes the primary winding 6 of transformer 7 inductively related to secondary winding 8 connected in the input circuit of the speechamplifier 9 comprising parallel connected tubes 10 and 11. The high frequency electron tube oscilllator for the transmitting system is represented by reference character 12 including oscillation circuit 14 containin inductance 15 and related capacities 16 an 17 connected between the input and output circuits of the oscillator and connected with the cathode circuit through conductor 18. The capacity 16 and grid condenser 19 are shunted by air core choke 20 and resistance 21. The oscillations developed from electron tube 12 and oscillating circuit 14 are impressed upon the high frequency amplification circuit 22 including parallel connected electron tubes 23 and 24. Provision is made for preventing reaction from the second or power stage of high frequency amplification 25 upon the input circuit of the first stage of high frequency amplification 22 and the other electron tube circuits in the system by connecting the grid circuits of tube 23 and 24 with the plate circuits thereof through an anti-resonating circuit 26 and 27. Elements 26 and 27 form with the internal grid-plate capacity an anti-resonant circuit series tuned to the transmitted high frequency. The power amplifier 25 consists of parallel electron tubes 28 and 29 arranged to impress high frequency energy at large. amplitude upon the antenna system 30` through inductively coupled coils 31 and`32 adjusted forv transmission offrequencies at `which the transmitting system operates. That is, it should be preferably tuned tothe mean transmission frequency but broadly enough to efficiently transmit the entire transmitted band. In order to prevent the high frequency current from being shunted away from that part of the plate circuit of the power amplifier 25 which is connected to the antenna system 30, We provide a high frequency choke coil 33 in the output circuit of the power amplifier circuit 25. Inasmuch as large voltages are impressed upon this choke and as it is required to carry considerable current, it has been found desirable to construct it of several coils in parallel, each of the coils of which may consist of several small coils in series. Filament lighting current for all of the electron tubes in the transmitting system is obtained from generator 34 through transformer 35 and busses 36. Plate current generator 37 is provided having a high inductance choke coil 38 connected in circuit therewith in the common lead to the speech frequency bank of power tubes and the high frequency bank of power tubes. The plate energy for the oscillator 12 and high frequency amplifier 22 is supplied from generator 39 through choke coils 40 and 41 respectively.

Shunted across the input circuit of the power amplifier 25 we provide a potentiometer circuit 42 consisting of parallel connected resistances 43 and 44 in series with air core choke 45. Terminal 46 of the potentiometer circuit 42 is normally at negative potential while terminal 47 is normally at positive potential. Variable contacts 48 and 49 are provided to include varying portions of resistances 44 and 43 respectively. The slidable contact 48 is connected through bus 50 with the end of the secondary winding 5 in the input circuit of the modulator tube 1` permitting variations of potential upon the grid of said tube. Slidable contact 49 on resistance 43 is connected through bus 51 with slidable contact 52 on secondary winding 8 in the input circuit of speech frequency amplifier 9, enabling varying potentials to be placed upon the grids of tubes 10 and 11.

It will be observed that the negative potentials for the grids of the tubes 1, 10, 11, 28 and 29 comprising the speech amplifier and the power amplifier is derived from the unitary potentiometer circuit 42. A relatively large continuous fiow of current passes through potentiometer circuit 42 which insures a steady negative potential at the points 48 and 49 in resistances 44 and 43 respectively with a corresponding negative grid potential for the modulator tube 1 and speech amplifier tubes 10 and 11.

`This current results from the difference in potential between the filament and grid of tube 25, on which grid a large negative p0- tential tends to accumulate as the negative electrons, which are attracted to the grid llO ' low amplitudes.

when ositive potentials are impressed from ampli er 22l are trapped thereon by condenser 53, during the time that negative potentials are similarly impressed from am.-

lifier 22. The potentials of the grids may e further adjusted by means of the fixed potential source 54. Automatic compensation for the effects of momentary high potentials impressed upon the modulator l from the speech circuit 2while causing an unusually large amplitude of energy in the plate circuit of the ower amplifier 25 will also cause a series of) momentarily large impulses of current to flow to the grids of tubes 28 and 29. This results in increased current flow inthe potentiometer circuit 42 and a consequent momentarily increased negative potential upon the rids of tubes 1, 10, l1, 28 and 29 which will tend to increase the impedance of all of the tubes, proportionately changing the characteristics at which the system functions. This change in the operating characteristic of the s stem takes place instantaneously upon c an e in the electrical .condition of the speec frequency circuit.

An advantage of the above described operation not considered before is that the grid bias on the amplifiers may be normally such as to allow sufficient amplification of the low amplitude consonant-modulated high frequency current while, when alarge amplitude vowel-modulated current has to be am lified, the grid bias is instantly increase thereby limiting the grid current and accordingly preventing the overloading of the preceding tube. There may be realized a net gain in amplification of the large amplitude signal over what would be obtained by leaving the grid bias fixed at a value giving maximum amplification for While we have described our invention in certain particular embodiments we desire that it be understood that modifications in the several arrangements may be made and that no limitations upon the invention other than are imposed by the scope of the ap ended claims are intended.

hat is claimed is:

1. In a signaling system means including space discharge devices having grid electrodes for supplying 'modulated -high frequency waves to a power amplifier, a gridcathode path in said' power amplifier, and

connections from 'said path to said grids whereby suitable working or biasing potentials are applied to said grids.

2. A signaling system comprising, in: combination, a plurality of electron tubes including a modulator,` a speech amplifier-and a power amplifier, said power amplifier having an input and output circuit, means connected in the input circuit of said power amplier for determining the operating potential therein and means connected to said first mentioned means for determining thc operating potential of said other tubes.

3. iVaVe transmitting apparatus, including a plurality of electron tubes, a power amplifier having an input and an output circuit, and means connected in thc input circuit of said power amplifier for determining the operating potentials of said tubes. y

4. In combination, a plurality yof electron tubes including a modulator, a speech amplifier and a power amplifiensaid power amplifier having an input and output circuit, means connected in the input circuit of said power amplifier for fixing the operating potential of said power amplifier, and

variable means connected with portions of f said first mentioned means for fixing the operating potential of said modulator and speech amplifier.

5. In a signaling system, in combination a plurality of electron tubes, apowcr amplifier Vhaving input and output circuits, means connected in shunt with the input circuit of said power amplifier for determining the passage of current in said input'circuit, and means variably connected to said first nientioned means for determining the operating potentials of said other tubes.

6. Radio transmitting apparatus, comprising in combination an antenna system, a source of sustained oscillations, an electron tube modulator and speech amplifier connected with said source of sustained oscillations for producing signals, means for increasing the amplitude of the modulated signal energy, power amplifier means having a grid circuit and' an output circuit for increasing the effect of said amplified signals on said antenna system, means connected in the grid circuit of said power amplifier for determining the potential thereof, and

means connected with said first mentioned means for fixing the operating potential of said modulator and speech amplifier.

7. Radio transmitting apparatus, comprising in combination an antenna system, a source of sustained oscillations, an electron tube modulator and speech amplifier connected with said source of sustained oscillations for producing signals, means for increasing the amplitude of the modulated signal energy, power amplifier means having aigrid circuit and an output circuit for increasing the effect of said amplified signals on said antenna system, and means connected in the grid circuit of said power amplifier for automatically fixing the operating potential or said modulator and speech amplifier.

8.- Radio transmitting apparatus, com-i prising in combination an antenna system, a source of sustained oscillations, an electron tube modulator and speech amplifier system, combination of a plurality of electron tubes including a modulator, a speech amplifier and 'a power amplifier. a grid circuit for each of said tubes, and means connected in the grid, circuit of said power amplifier for maintaining said grids for each of said tubes at negative potential.

10. Signaling apparatus, including a plurality of electron tubes, each having grld, filament and plate electrodes, a power amplifier having an input and an output circuit and means connected in the input circuit of said power amplifier for negatively biasing the grid electrodes of all of said tubes.

l1.` Signaling apparatus, comprising in combination a plurality of electron tubes, cach having grid, filament and plate electrodes and including a modulator, an amplifier connected to said modulator, and a power amplifier having input and output circuits, and unitary means connectedin the input circuit of said power amplifier for negatively biasing the grid electrodes of said power amplifier and correspondingly biasing the grid electrodes for each of said other tubes.

12. Signaling apparatus, comprising in combination a lurality of electron tubes each having grid, filament and plate electrodes, an electron tube power amplifier having input and output circuits. and means connected in shunt with the input circuit of said power amplifier for controlling the grid potential of the tubes in said power amplifier and the grid potential of each of said other tubes.

13. Radio transmitting apparatus, comprising in combination an antenna system, a plurality of electron tubes having grid, filanient and plate electrodes constituting a source of sustained oscillations, a modulator, an amplifier connected with said modulator and cach connected with said source of sustained oscillations for producing signals, means for increasing the amplitude of the modulated signal energy, power amplifier means having a grid circuit and an output circuit for increasing the effect of said amplified signals on said antenna system, means connected in the grid circuit of said power. amplifier for negatively biasing the grid electrodes thereof, and connections between said last mentioned means and the grid electrodes of said other tubes for impressing corresponding negative potentials thereon.

14. In a signaling system, the combination of a plurality of electron tubes including a modulator, a speech amplifier and a power amplifier, a grid circuit for each of said tubes, and means connected in the grid circuit of said power amplifier operative upon increases in amplitude of energy in said speech amplifier for increasing the negative potential upon the grids of all of said tubes.

15. In a signaling system, the combination ,of a plurality of electron tubes each having grid, filament and plate electrodes, comprising a modulator, an amplifier connected to said modulator and a power amplifier, and means connected to said power amplifier responsive to increases in energy in said modulator for simultaneously changing the operating potential of all of' said tubes.

16. Radio transmitting apparatus, comprising in combination an antenna system, a plurality of electron tubes having id, filament and plate electrodes constltuting a source of sustained oscillations, a modulator, an amplifier connected with said modulator and with said source of sustained oscillations for producing signals, means for increasing the amplitude of the modulated signal energy, power amplifier means having a grid circuit and anoutput circuitVV for increasing the edeet of said amplified signals on said antenna system, and means connected in the grid circuit of said power amplifier for compensating for the effects of excess energy in said modulator by proportionally changing the operating potential upon each of said grid electrodes.

17. Radio transmitting apparatus, comprising in combination an antenna system, a

plurality of electron tubes having grid, filament .and plate electrodes constituting a source of sustained oscillations, a modulator and speech amplifier connected with said source of sustained oscillations for producing signals, means for increasing the amplitude of the `modulated signal energy, power amplifier means having a grid circuit and an output circuit for increasing the effect of said amplified signals on said antenna system, a group of parallel connected resistance units located in the grid circuit of said power amplifier, and connections between separate resistance units of said group and the grid electrodes of said modulator and speech amplifier respectively whereby all of said grid electrodes are negatively biased from a common source.

In witness whereof, we hereunto subscribe our names this 9th day of June, A. D. 1924. 

